1. Field of the Invention
The present invention relates to a method of manufacturing a film with a coating layer by coating coating-liquid to the surface of a web (film), which is continuously transported, with an extrusion type die, and more particularly, to a method of manufacturing a film with a coating layer that simultaneously coats a plurality of coating layer to a web.
2. Description of the Related Art
Until now, a bar coater type coating device, a reverse roll coater type coating device, a gravure roll coater type coating device, and a slot die coater type coating device such as an extrusion coater type coating device are known as coating devices that coat or form an coating film (coating layer) having a desired thickness to the surface of a flexible support (hereinafter, also referred to as a web).
Among them, a slot die coater type coating device can coat a thin film (thin layer) at a high speed in comparison with other type coating devices. For this reason, the slot die coater type coating device is widely used. In recent years, the demand for a liquid crystal monitor has increased with the spread of personal computers and the reduction of the thickness of home televisions. Accordingly, the demand for optical films, such as a polarizing film and an optical compensation film, requiring the formation of a thin film has also increased. For this reason, a slot die coater type coating device, which can form a thin film and can form a multilayer film, has been under the spotlight.
There is a bead depressurization overbite type slot die as a slot die that has been used often in the past in this slot die coater type simultaneous multilayer coating device (see JP1997-511681A (JP-H09-511681A) and JP2003-260400A).
An overbite slot die refers to, for example, a slot die where a tip portion (referred to as a lip) of a die block (referred to as the most downstream block), which is provided on the most downstream side in the advancing direction of the web, of die blocks (simply referred to as blocks) constituting a slot die protrudes downward as compared to a lip of a die block (referred to as an adjacent block) adjacent to the most downstream block.
In other words, for example, a slot die where a distance between the lip of the most downstream block and the web is shorter than a distance between the adjacent block and the web is referred to as an overbite slot die.